In the examination of the human eyes, in particular of the retinas of the same, fundus imaging is an essential tool. For this purpose, Scanning Laser Ophthalmoscopes (SLO) have been recently developed in order to rapidly obtain high resolution images of the ocular fundus and its internal structures.
Among the possible tests that a SLO may perform, the assessment of the function of the macular area of the human retina, in order to detect presence of any macular degeneration, preferably in its early stages, is an extremely important one, in order to obtain an indication on whether the macular function is normal, suspect or abnormal.
Generally, the assessment above described is obtained acquiring both images of the retinas of the patient and a more subjective assessment of the retinas' functionality projecting on the patient's retinas different stimuli.
U.S. Pat. No. 5,568,208 in the name of Frans J. Van de Velde discloses a modified laser ophthalmoscope which expands the range of clinical applications of the conventional scanning laser ophthalmoscope, being able of presenting the scanning laser raster with graphics to the retina and simultaneously allowing the observation of the anterior segment on the display monitor. The device, including a beam splitter, infrared light source, scanning laser ophthalmoscope, CCD camera, and optical filters, determines unambiguously in real-time the entrance pupil of the Maxwellian view scanning laser ophthalmoscope. The location of the entrance pupil and stimulus position on the retina can be moved independently.
Applicants have noted that the stimuli and the background projected onto the retina are not independent one from the other.
U.S. Pat. No. 6,705,726 in the name of Nidek Co., Ltd. relates to a novel instrument for the examination of the eye, namely the retina. The instrument features a LCD display for projection of various types of patterns and stimuli via an optical system onto the retina. The retina can be visualized by live IR image sequences as well as by visible light still frame images. It combines five examination types within one instrument, namely a perimetry examination, a microperimetry examination, a fixation stability examination, a scotoma boundary detection and psychophysical examinations.
Applicants have noted that the presence of an LCD to produce the stimuli limits the possibility of determining their location to a discrete number of “points” which depends on the pixel of the LCD screen.
U.S. Pat. No. 7,284,859 in the name of Physical Sciences, Inc., discloses a system and a method for providing a line-scanning laser ophthalmoscope (LSLO). The LSLO uses a substantially point source of light, such as infrared laser or a super-luminescent diode. The point source is expanded to a line. The LSLO scans the line of light in a direction perpendicular to a line across a region of an eye having an undilated pupil. The reflected light is received confocally, using monostatic beam geometry. A beam separator, such as a turning prism or a mirror, diverts one of the incoming light and the reflected light to separate the lights. An optical stop prevents non-confocally received light from reaching a one-dimensional detector, such as a linear CCD array. An electrical signal responsive to the output light at each of a plurality of locations along the line of output light is processed to provide images of the scanned portion of the eye.